Influence of Mechanical Activation on Synthesis of Compounds in the B/C - Mg/Al/Ca System

Abstract

<p>The possibility of mechanochemical synthesis and influence of mechanical activation on thermal synthesis of borides and boron carbides of mass-low metals is investigated. The opportunity of mechanochemical synthesis in the mill AGO-2 of such compounds as AlB<sub>2</sub> and CaC<sub>2</sub>B<sub>2</sub> is established. Influence of mechanical activation in the mill SPEX 8000 on synthesis of such compound as Mg<sub>0.5</sub>Al<sub>0.5</sub>B2 is shown. Mechanical activation also influences on the process of thermal synthesis: compound Mg<sub>0.5</sub>Al<sub>0.5</sub>B<sub>2</sub> is obtained in the conditions inaccessible to traditional thermal synthesis; formation of compound Mg<sub>1-x</sub>Al<sub>x</sub>B<sub>2</sub> in literature up to x = 0.4 was established on shifts of reflexes (002) and (110) pure MgB<sub>2</sub> aside the large corners; in our case x = 0.5 and as it was necessary to expect shifts of these reflexes exceeds shifts measured in literature only for x ≤ 0.4. Features of synthesis in systems containing metal magnesium are considered. The opportunity of application of crystalline boron for mechanochemical synthesis of borides and boron carbides of mass-low metals is established, that it was not represented probable to make in its ceramic synthesis. We revealed also that thermal analysis in conditions of helium results in crystallization almost all activated samples, and the analysis of received X-ray reflexes unambiguously allows to assert that mechanical activation accelerates synthesis of reaction products in the investigated systems in comparison with the traditional methods of its synthesis.</p>